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floor, floorf, floorl

From cppreference.com
< c‎ | numeric‎ | math
 
 
 
Common mathematical functions
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Nearest integer floating-point
floor
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Defined in header <math.h>
float       floorf( float arg );
(1) (since C99)
double      floor( double arg );
(2)
long double floorl( long double arg );
(3) (since C99)
Defined in header <tgmath.h>
#define floor( arg )
(4) (since C99)
1-3) Computes the largest integer value not greater than arg.
4) Type-generic macro: If arg has type long double, floorl is called. Otherwise, if arg has integer type or the type double, floor is called. Otherwise, floorf is called.

Contents

[edit] Parameters

arg - floating-point value

[edit] Return value

If no errors occur, the largest integer value not greater than arg, that is ⌊arg⌋, is returned.

Return value
Argument

[edit] Error handling

Errors are reported as specified in math_errhandling.

If the implementation supports IEEE floating-point arithmetic (IEC 60559):

  • The current rounding mode has no effect.
  • If arg is ±∞, it is returned, unmodified.
  • If arg is ±0, it is returned, unmodified.
  • If arg is NaN, NaN is returned.

[edit] Notes

FE_INEXACT may be (but isn't required to be) raised when rounding a non-integer finite value.

The largest representable floating-point values are exact integers in all standard floating-point formats, so this function never overflows on its own; however the result may overflow any integer type (including intmax_t ), when stored in an integer variable.

[edit] Example

Run this code
#include <math.h>
#include <stdio.h>
 
int main(void)
{
 printf ("floor(+2.7) = %+.1f\n", floor(2.7));
 printf ("floor(-2.7) = %+.1f\n", floor(-2.7));
 printf ("floor(-0.0) = %+.1f\n", floor(-0.0));
 printf ("floor(-Inf) = %+f\n", floor(-INFINITY));
}

Possible output: 

floor(+2.7) = +2.0
floor(-2.7) = -3.0
floor(-0.0) = -0.0
floor(-Inf) = -inf

[edit] References

  • C23 standard (ISO/IEC 9899:2024):
  • 7.12.9.2 The floor functions (p: TBD)
  • 7.25 Type-generic math <tgmath.h> (p: TBD)
  • F.10.6.2 The floor functions (p: TBD)
  • C17 standard (ISO/IEC 9899:2018):
  • 7.12.9.2 The floor functions (p: TBD)
  • 7.25 Type-generic math <tgmath.h> (p: TBD)
  • F.10.6.2 The floor functions (p: TBD)
  • C11 standard (ISO/IEC 9899:2011):
  • 7.12.9.2 The floor functions (p: 251)
  • 7.25 Type-generic math <tgmath.h> (p: 373-375)
  • F.10.6.2 The floor functions (p: 526)
  • C99 standard (ISO/IEC 9899:1999):
  • 7.12.9.2 The floor functions (p: 232)
  • 7.22 Type-generic math <tgmath.h> (p: 335-337)
  • F.9.6.2 The floor functions (p: 463)
  • C89/C90 standard (ISO/IEC 9899:1990):
  • 4.5.6.3 The floor function

[edit] See also

(C99)(C99)
computes smallest integer not less than the given value
(function) [edit]
(C99)(C99)(C99)
rounds to nearest integer not greater in magnitude than the given value
(function) [edit]
(C99)(C99)(C99)(C99)(C99)(C99)(C99)(C99)(C99)
rounds to nearest integer, rounding away from zero in halfway cases
(function) [edit]
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